I started off this cycle with the intention of writing "Why X" addenda for every school I'm applying to. It's worked out well for some schools, but for others, I'm having trouble finding information specific enough to relate to my interests, ie something beyond "X law school and is a leader in Y law and has a commitment to interdisciplinary education." Do you guys think that a vague Why X statement can hurt, or will it always be neutral or positive?

If a "why X' essay feels tacked-on I imagine it could rub some adcomms the wrong way. So a mediocre "why X" essay could definitely hurt I think. If your "why X" essay would be vague and not feel like a ringing endorsement of the school then don't bother writing one.